A probabilistic framework for estimating the residual drift of idealized SDOF systems of non‐degrading conventional and damped structures          下载免费PDF全文

Jack Wen Wei Guo  Constantin Christopoulos 《地震工程与结构动力学》2018,47(2):479-496

This paper presents a general framework for predicting the residual drift of idealized SDOF systems that can be used to represent non‐degrading structures, including those with supplemental dampers. The framework first uses post‐peak oscillation analysis to predict the maximum ratio of residual displacement to the peak transient displacement in a random sample. Then, residual displacement ratios obtained from nonlinear time‐history analyses using both farfield and near‐fault‐pulse records were examined to identify trends, which were explained using the oscillation mechanics of SDOF systems. It is shown that large errors can result in existing probability models that do not capture the influence of key parameters on the residual displacement. Building on the observations that were made, a general probability distribution for the ratio of residual displacement to the peak transient displacement that more accurately reflects the physical bounds obtained from post‐peak oscillation analysis is proposed for capturing the probabilistic residual displacement response of these systems. The proposed distribution is shown to be more accurate when compared with previously proposed distributions in the literature due to its explicit account of dynamic and damping properties, which have a significant impact on the residual displacement. This study provides a rational basis for further development of a residual drift prediction tool for the performance‐based design and analysis of more complex multi‐degree‐of‐freedom systems.  相似文献   

Seismic shear distribution among interconnected cantilever walls of different lengths          下载免费PDF全文

Katrin Beyer  Sabrina Simonini  Raluca Constantin  Avigdor Rutenberg 《地震工程与结构动力学》2014,43(10):1423-1441

Mid‐rise to high‐rise buildings in seismic areas are often braced by slender reinforced concrete (RC) walls, which are interconnected by RC floor diaphragms. In design, it is typically assumed that the lateral forces are distributed in proportion to the wall's elastic stiffness. Pushover analyses of systems comprising walls of different lengths have, however, shown that large compatibility forces can develop between them, which should be considered in design, but the analyses have also shown that the magnitude of the computed forces is very sensitive to the modelling assumptions. Using the results of a complex shell element model as benchmark, different simple hand‐calculation methods and inelastic beam element models are assessed and improved to yield reliable estimates of the base shear distribution among the individual walls comprising the interconnected wall system. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

The dynamics of waves interacting with the Equatorial Undercurrent     

A Constantin  R.S. Johnson 《地球物理与天体物理流体动力学》2015,109(4):311-358

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Geomorphologic map of the 1<Superscript>st</Superscript> Mutnaya River,Southeastern Kamchatka,Russia     

Gheorghe Romanescu  Sergey Chalov  Cristian Constantin Stoleriu  Alin Mihu-Pintilie  Silvia Eleonora Angileri  Yulia Kuznetsova  Mariaelena Cama  Michael Maerker 《山地科学学报》2017,14(12):2373-2390

The Kamchatka Peninsula–situated in the Pacific “Ring of Fire”–has 29 active and over 400 extinct volcanoes. Since it is situated in the northeastern extremity of Russia, in subarctic climate, the volcanic landforms are overprinted by the 446 glaciers. This research focuses on the 1^stMutnaya catchment which drains the southern slopes of two active volcanoes: Avachinsky and Koryaksky. Those volcanoes are a permanent threat for the cities of Petropavlovsk and Elizovo, which are the 2 of 3 cities of the peninsula. Hence, most of the studies carried out in the area dealt with the natural hazards and only few focus on landscape evolution. Thus, the purpose of this study was to elaborate a cartographic approach which integrates classic geomorphology with state of the art GIS and remote sensing techniques. As result, different landforms and related processes have been analysed and included in the first general geomorphologic map of the 1^stMutnaya catchment.  相似文献   

Petrography of alluvial sands as a past and present environmental indicator: Case of the Loire River (France)     

Jean-Jacques MACAIRE  Isabelle GAY-OVEJERO  Michel BACCHI  Constantin COCIRTA  Luc PATRYL  Stéphane RODRIGUES 《国际泥沙研究》2013,28(3):285-303

Four sample sets of the Upper and Middle Loire river sands were analyzed in order to study the impact of natural and anthropogenic factors on their petrographic composition in space (on an 800 km stretch) and time. Composition was determined by modal analysis of three sand-size fractions using a polarizing optical microscope and calculated for each sample (“standard sand” = Sst). The watershed is composed mainly of endogenic (Massif Central) and sedimentary (southern Parisian Basin) rocks. B-set sands collected in channels for different water flows in 1996 show that Sst compositions vary by only 5 %. Present-day sands in the Upper Loire and Middle Loire have very high petrographic immaturity comparing to others worldwide fluvial sands, although bio-climatic conditions favor sand maturation by source-rock weathering in the watershed. This shows the strong impact of the Massif Central on sediment yield due to relief rejuvenation as a consequence of the formation of the Alps during the Quaternary. Fluvial sands stored during the Weichselian and the Holocene in the Middle Loire floodplain, although partly weathered since their deposition, show higher inputs from the endogenic rocks of the Massif Central than present-day deposits. This can be explained by Weichselian periglacial conditions and the development of crop farming since the Neolithic, which favored mechanical erosion, particularly in the Massif Central which is characterized by a cold, humid climate and steep slopes. The upstream-downstream change in the composition of presently deposited sand is low in the diked area. It shows however that basalt and some heavy mineral grains are vulnerable to abrasion during transport and indicates a marked sediment yield from ancient sediment stored in the floodplain. This is in line with the high incision of the river bed over the last 150 years partly due to dam construction and aggregate mining.  相似文献   

Performance spectra based method for the seismic design of structures equipped with passive supplemental damping systems     

Jack Wen Wei Guo  Constantin Christopoulos 《地震工程与结构动力学》2013,42(6):935-952

A new direct performance‐based design method utilizing design tools called performance‐spectra (P‐Spectra) for low‐rise to medium‐rise frame structures incorporating supplemental damping devices is presented. P‐Spectra are graphic tools that relate the responses of nonlinear SDOF systems with supplemental dampers to various damping parameters and dynamic system properties that structural designers can control. These tools integrate multiple response quantities that are important to the performance of a structure into a single compact graphical format to facilitate direct comparison of different potential solutions that satisfy a set of predetermined performance objectives under various levels of seismic hazard. An SDOF to MDOF transformation procedure that defines the required supplemental damping properties for the MDOF structure to achieve the response defined by the target SDOF system is also presented for hysteretic, linear viscous and viscoelastic damping devices. Using nonlinear time‐history analyses of idealized shear structures, the accuracy of the transformation procedure is verified. A seismic performance upgrade design example is presented to demonstrate the usefulness of the proposed method for achieving design performance goals using supplemental damping devices. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Shake table testing and numerical simulation of a self‐centering energy dissipative braced frame     

Jeffrey Erochko  Constantin Christopoulos  Robert Tremblay  Hyung‐Joon Kim 《地震工程与结构动力学》2013,42(11):1617-1635

The self‐centering energy dissipative (SCED) brace is a new steel bracing member that provides both damping to the structure and a re‐centering capability. The goal of this study was to confirm the behavior of SCED braces within complete structural systems and to confirm the ability to model these systems with both a state‐of‐the‐art computer model as well as a simplified model that would be useful to practicing engineers. To these ends, a three‐story SCED‐braced frame was designed and constructed for testing on a shake table. Two concurrent computer models of the entire frame were constructed: one using the opensees nonlinear dynamic modeling software, and a simplified model using the commercial structural analysis software sap2000 . The frame specimen was subjected to 12 significant earthquakes without any adjustment or modification between the tests. The SCED braces prevented residual drifts in the frame, as designed, and did not show any significant degradation due to wear. Both numerical models were able to predict the drifts, story shears, and column forces well. Peak story accelerations were overestimated in the models; this effect was found to be caused by the absence of transitions at stiffness changes in the hysteretic model of the braces. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Origin of magmatic sulfides in a Proterozoic island arc—an example from the Portneuf–Mauricie Domain,Grenville Province,Canada     

Anne-Aurélie Sappin  Marc Constantin  Thomas Clark 《Mineralium Deposita》2011,46(3):211-237

The Portneuf–Mauricie Domain (PMD), located in the south-central part of the Grenville province, contains Mesoproterozoic Ni–Cu ± platinum-group element (PGE) prospects hosted in a variety of plutonic intrusions (layered, with simple structures, or zoned) and emplaced in a mature island arc setting. A two-stage model is envisaged to explain the formation of magmatic sulfides. An early loss of a small amount of sulfides in the conduits of primitive, hydrous mantle-derived melts under high fO₂, resulted in depletion of the magmas in chalcophile and precious metals (Cu/Pd ratios vary from initial mantle values up to 1.6 × 10⁶). Then, nearer the mineralized zones, the magmas interacted with sulfide-bearing country rocks, resulting in felsification of the magmas, assimilation of crustal sulfur (δ ³⁴S values up to +5.5‰), and the formation of an immiscible sulfide liquid. Liquid-sulfide formation was followed by variable interactions between the silicate and sulfide magmas, which were responsible for the enrichment of sulfides in Ni, Cu, and, locally, PGE. Indeed, low R factors are found for prospects hosted in intrusions with a simple internal structure and in layered intrusions whereas high R factors are found for prospects hosted in zoned intrusions. Finally, sulfide melt may have been partly incorporated into later pulses of magma and injected into shallow magma chambers to form the PMD prospects. The PMD prospects share common characteristics with other well-known deposits (Aguablanca, Vammala, Stormyrplunen, and deposits in Alaskan/Ural-type intrusions), attesting to the Ni, Cu, and PGE potential of deposits associated with subduction-zone settings.  相似文献   

Avalonian, Ganderian and East Cadomian terranes in South Carpathians, Romania, and Pan-African events recorded in their basement     

Ioan Balintoni  Constantin Balica 《Mineralogy and Petrology》2013,107(5):709-725

New U-Pb geochronology is used to refine the provenance and evolution of northwest Gondwana Pan-African terranes preserved in the South Carpathians of Romania. The Dr?g?an terrane of Avalonian affinity, from the Danubian domain of the South Carpathians originated in the Panthalassa Ocean and accreted to the Amazonian part of Rodinia not much before 800 Ma, when the F?ge?el orthogneiss was intruded, at around 807–810 Ma. After this event no other Neoproterozoic magmatic pulse is known in the basement of the Dr?g?an terrane. The Ganderian type Lainici-P?iu? terrane from the same domain of the South Carpathians, recorded magmatic pulses at 782 Ma, 739 Ma, 708 Ma, 639 Ma, 600–587 Ma and 574–568 Ma. The East Cadomian Sebe?-Lotru terrane from the Getic domain of the South Carpathians recorded magmatic pulses at 817 Ma, 768 Ma, 685 Ma, 620 Ma, 584 Ma and 550 Ma. Post 630 Ma the northwestern Gondwana margin evolved as an active continental margin at least until 550 Ma, but the pre-630 Ma magmatism could be associated to some island arcs docked with different pre-Gondwanan continental fragments. Independent of the tectonic setting, the post 750 Ma orogens dated in the basement of the peri-Gondwanan terranes are discussed in the frame of the Cadomian orogens, as constituents of the Pan-African orogens in a broader sense. The detrital zircon may also record magmatic pulses from Pan-African orogens other than the Cadomian ones.  相似文献   

Carpathian peri-Gondwanan terranes in the East Carpathians (Romania): A testimony of an Ordovician,North-African orogeny     

Ioan Balintoni  Constantin Balica 《Gondwana Research》2013,23(3):1053-1070

The eastern branch of the Romanian Carpathians – the East Carpathians – is essentially an Alpine thrust and fold belt made up in its median part by a Crystalline–Mesozoic zone. This, in turn, is built up by several Alpine nappes (top to bottom): the Wildflysch, Bucovinian, Subbucovinian and Infrabucovinian. In the basement of the Bucovinian and Subbucovinian nappes the following Variscan tectonic units have been identified (top to bottom): Rar?u, Putna, Pietrosu Bistri?ei and Rodna. The Infrabucovinian nappes comprise the Rar?u nappe only. The Alpine nappes have an eastward vergence, opposite to the Variscan ones (present coordinates). In terms of pre-Variscan terranes distribution, the Rar?u nappe involved the Bretila terrane basement and its late Paleozoic cover, Putna the Tulghe? terrane basement, Pietrosu Bistri?ei the Negri?oara terrane basement and Rodna the Rebra terrane basement. These terranes originated along northwestern Gondwana margin during some Ordovician thermotectonic events. They do not represent Cadomian terranes and we call them Carpathian-type terranes. Two igneous protoliths from Bretila terrane basement (i.e. Anie? orthogneiss and H?ghima? granitoid) yield U/Pb LA-ICP-MS zircon ages of 462 ± 3 Ma and 469.2 ± 6.5 Ma, respectively. An orthogneiss from Tulghe? terrane basement yield 462.6 ± 3.1 Ma; the Pietrosu porphyritic orthogneiss from Negri?oara terrane basement yield 461.1 ± 5.2 Ma; and the Nichita? orthogneiss from Rebra terrane basement yield 447.9 ± 2.8 Ma. All these ages suggest the magma crystallization time. Two paragneisses from the Rebra terrane basement show a detrital zircon age distribution characteristic of a NE-African provenance. Regarding the tectonic settings, the lithology of the Bretila terrane suggests a magmatic arc on a continental margin, while of the Tulghe? terrane suggests a back arc environment, and those of the Rebra and Negri?oara terranes suggest a passive continental margin. An Ordovician metamorphism of medium grade (staurolite–kyanite zone) affected the basements of Bretila, Negri?oara and Rebra terranes, whereas a low grade (chlorite to biotite zone) event affects the Tulghe? terrane. With regard to the Variscan orogeny, the existence of a Paleotethys suture is proposed within the metamorphic basement of the East Carpathians. In this interpretation, the Bretila terrane was the upper plate, the Rebra and Negri?oara terrane pair formed the lower plate and the Tulghe? terrane was a component of the suture. The Variscan thermotectonic events reflect isothermal decompression with andalusite + cordierite in the basement of the Rebra terrane and retrogression in the basement of the other terranes.  相似文献